1. Field of the Invention
The present invention relates in general to a silencing device of a vacuum cleaner for effectively suppressing noises of the vacuum cleaner such as caused by a suction motor, suction air flow and exhaust air flow and, more particularly, to an improved structure in such a silencing device of the vacuum cleaner for improving the noise suppressing effect.
2. Description of the Prior Art
In the prior art, there have been proposed and widely used several types of silencing devices for vacuum cleaners.
For example, Japanese U.M. Publication No. Sho. 62-45631 (applied on Oct. 23, 1981 and published on Dec. 7, 1987) discloses a silencing device for a vacuum cleaner which is shown in FIG. 1 of the accompanying drawings.
As shown in FIG. 1, the conventional vacuum cleaner comprises a suction motor 2' provided in a cleaner casing 1'. In FIG. 1, the exhaust port provided on the back of the casing 1' for exhausting the purified air to the outside is designated by the numeral 3'. The suction motor 2' for generating suction force communicates with the exhaust port 3' through both an air path 4' and an exhaust silencer 5'. The exhaust silencer 5' defines an exhaust path 6' therein. In the above silencing device, the exhaust path 6' of the exhaust silencer 5' is inclined upwardly from the air path 4' at an obtuse angle. With the inclined relationship between the exhaust path 6' and the air path 4' of the casing 1', it is possible to suppress the turbulence noise caused by the exhaust air flow having already passed the suction motor 2'. In the above silencing device, the turbulence noise is partly absorbed and suppressed by a noise absorbing material 7'.
However, the above silencing device for a vacuum cleaner, while partly absorbing and suppressing the exhaust noise caused by the exhaust air flow having passed the suction motor 2', nevertheless has a problem that the exhaust air flow should pass through a relatively short path and be exhausted to the outside of the casing 1' from only one exhaust port 3' of the casing 1', so that it is impossible to achieve the desired noise absorbing and suppressing effect.
The conventional silencing device has no means for suppressing the suction noise caused by the suction motor 2' so that the suction noise travels to the outside of the casing 1'. Furthermore, the conventional silencing device cannot effectively absorb and suppress the noise caused by the exhaust air flow of the suction motor 2'. In this regard, a vacuum cleaner equipped with the above silencing device cannot prevent the emission of excessive noise to the outside during its operation.
In addition, the conventional silencing device cannot suppress the noise caused by the suction air flow generated in the dirt collection chamber of the cleaner when the cleaner sucks dirt-laden air. The vacuum cleaner equipped with the above silencing device thus emits the excessive noise to the outside during its operation and this is not only annoying to the user, but also deteriorates the quality of the vacuum cleaner.